Hair Particles And Compositing layers?

Im having a trouble trying to move the Hair particles from my caharacter to a new layer. the hair particles are atached by vertex group to my main mesh so i can´t move them from a layer to another separately. im trying to do this to be able to render the hair of my character in cyles with cpu ,and the rest of the character with gpu.
any advices?

thanks in advance¡¡